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The Jinshajiang–Red River alkaline igneous belt and the associated Cenozoic Cu–Au mineralization are located in an intra-continental strike-slip fault zone in SW China. The Ce 4 + /Ce 3 + ratios of zircon from representative Cu-mineralized, Au-mineralized and barren porphyry intrusions from the belt indicate that the Cu–Au ore-bearing porphyry intrusions had much higher fO 2 of magma than the barren porphyry intrusions. Elemental and Sr–Nd isotope ratio data indicate that both the Cu–Au ore-bearing and barren porphyry intrusions were derived from partial melts of the ancient enriched metasomatized mantle sources (EMII type). The mantle source was possibly modified by subduction of the Paleo-Tethyan oceanic slab beneath the Changdu–Simao block between the early Permian and the late Triassic. The oxygen fugacity of the magma was likely related to the redox state of the source, and the different fO 2 calculated for the magmas that gave rise to Cu–Au ore-bearing and barren porphyry intrusions are a product of magmas from the different sources. The sources of the barren porphyry intrusions were influenced mainly by the slab-derived fluids, whereas the sources of the Cu–Au ore-bearing porphyry intrusions were modified by both the slab-derived fluids and slab-derived melts. Cenozoic strike-slip faulting in this region caused lithospheric-scale extension and upwelling of the asthenosphere; the heat produced by this process produced partial melts of the ancient enriched metasomatized mantle sources, resulting in the emplacement of alkaline porphyry intrusions and associated Cu–Au mineralization at ~ 40–30 Ma. [ABSTRACT FROM AUTHOR]

The Jinshajiang-Red River alkaline igneous belt in the eastern Indian-Asian collision zone, of southwestern China, hosts abundant, economically important Cu-Mo-Au mineralization of Cenozoic age. Major- and trace-element compositions of titanites from representative Cu-mineralized intrusions determined by LA-ICP-MS show higher values for FeO/AlO, ΣREE + Y, LREE/HREE, Ce/Ce*, (Ce/Ce*)/(Eu/Eu*), U, Th, Ta, Nb and Ga, and lower values for AlO, CaO, Eu/Eu*, Zr/Hf, Nb/Ta and Sr than those for titanites from barren intrusions. Different ΣREE + Y, LREE/HREE, U, Th, Ta and Nb values of titanites between Cu-mineralized and barren intrusions were controlled mainly by the coexisting melt compositions. However, different Sr concentrations and negative Eu anomalies of titanites between Cu-mineralized and barren intrusions were most probably caused by different degrees of crystallization of feldspar from melts. In addition, different Ga concentrations and positive Ce anomalies of titanites between Cu-mineralized and barren intrusions were most likely caused by different magmatic fO conditions. Pronounced compositional differences of titanites between Cu-mineralized and barren intrusions can provide a useful tool to help discriminate between ore-bearing and barren intrusions at an early stage of exploration, and, thus, have a potential application in exploration for porphyry Cu deposits in the Jinshajiang - Red River alkaline igneous belt, and to other areas. [ABSTRACT FROM AUTHOR]